If your "testing" is prolonged, you might be better off to use 1/2 max rpm and alter your numbers by 50%. This will be less stressful on the engine and may attract less attention from the authorities.

 

Ok...I've figured it out. But first let me start where all the confusion began.

When installed, I was told that the setting was on neg 11

I looked at the switches and it displayed:
LEGEND: 0 = DOWN and 1 = UP
01010011

Taking the facts that were given to me, if this was neg 11 then I assumed that Down must mean on with respect to what I'm seeing here and the leading zero meant neg. This is where it all went wrong.


My test results are:

gear.......4.1 top speed ..............4.56 top speed

1....................43 mph.......................33 mph
2...................66 mph........................52 mph
3...................91 mph........................74 mph
4..................116 mph.....................93 mph
5..................138 mph.....................N/A mph
6..................165 mph (theoretical)...N/A mph

give a little break on my redlining on the first two gears, I may have not taken it all the way. The percentage change on gears 3 and 4 are above 20 percent.

So, this tells me the information I was given was wrong. Correctly anaylzing my dip switch settings again
01010011
I see this must mean I'm at 20.75 and the front zero means POSITIVE which would make sense with what you guys are saying and what I'm seeing.

So I changed it to

00101100
POSITIVE 11 percent! and now its correct.

A lot of descrepancy was in relying on the information that it was set to negative 11 and the data sheet really not specifying which way meant on or off.

 

Nate and xviper,

Thanks for the "POSITIVE" inputs guys !! . Thats what really helped me here, otherwised I'd still be believing it was suppose to be negative 11 percent compensation.

At 5000 rpms in 6th, I'm correctly reading 80-81 mph now.

 

I'm glad you got it all good! Speeding tickets suck!


My neighbor works for the D.O.T. and when I get mine installed next month, we're gonna measure the speedo down to the thousandth of a percent with his surveying equip. and post back so people know what the settings are right off the bat.

 

WOW!

(But what happens as your tires wear and their diameters change by 1%? )

 

tuff stuff. good work!

 

Interesting point, xviper. I wonder if a stock spedometer is calibrated to new or worn tires? If it's calibrated to new, then your actual speed would be lower than what the spedometer reads on worn tires.

 

Easiest way I've found to calibrate is with a GPS on a flat, empty stretch of road. Use 100mph on your GPS to make the math easier

 

I don't think it's enough to worry about. Generally, police give you about 5% leaway and 15% on the photoradar.
Digital speedometers tend to be fairly accurate until you get into triple digit speeds. The Vettes I had boasted an error 0%. I'm tending to think the S2000 is within 1% to 2%.

 

SO WERE SAYING 165 IS TOP SPEED?